hmm... a post written by an admin with unapproved attachments?
Anyway, to fix it, open Notifications.subs.php and find:
// Maillist format?
$maillist = !empty($modSettings['maillist_enabled']) && !empty($modSettings['pbe_post_enabled']);
if ($maillist)
require_once(SUBSDIR . '/Emailpost.subs.php');
replace the entire block with just:
require_once(SUBSDIR . '/Emailpost.subs.php');